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Subject[PATCH v5 4/7] pwm: pca9685: Reset registers to POR state in probe
Date
Reset the prescale and ON/OFF registers to their POR default state in
the probe function. Otherwise, the PWMs could still be active after a
watchdog reset and reboot, etc.

Signed-off-by: Clemens Gruber <clemens.gruber@pqgruber.com>
---
drivers/pwm/pwm-pca9685.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
index 7b14447f3c05..38aadaf50996 100644
--- a/drivers/pwm/pwm-pca9685.c
+++ b/drivers/pwm/pwm-pca9685.c
@@ -47,6 +47,7 @@
#define PCA9685_ALL_LED_OFF_H 0xFD
#define PCA9685_PRESCALE 0xFE

+#define PCA9685_PRESCALE_DEF 0x1E /* => default frequency of ~200 Hz */
#define PCA9685_PRESCALE_MIN 0x03 /* => max. frequency of 1526 Hz */
#define PCA9685_PRESCALE_MAX 0xFF /* => min. frequency of 24 Hz */

@@ -446,9 +447,11 @@ static int pca9685_pwm_probe(struct i2c_client *client,
reg &= ~(MODE1_ALLCALL | MODE1_SUB1 | MODE1_SUB2 | MODE1_SUB3);
regmap_write(pca->regmap, PCA9685_MODE1, reg);

- /* Clear all "full off" bits */
+ /* Reset ON/OFF registers to HW defaults (only full OFF bit is set) */
+ regmap_write(pca->regmap, PCA9685_ALL_LED_ON_L, 0);
+ regmap_write(pca->regmap, PCA9685_ALL_LED_ON_H, 0);
regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_L, 0);
- regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, 0);
+ regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, LED_FULL);

pca->chip.ops = &pca9685_pwm_ops;
/* Add an extra channel for ALL_LED */
@@ -470,8 +473,10 @@ static int pca9685_pwm_probe(struct i2c_client *client,
/*
* The chip comes out of power-up in the sleep state,
* but force it to sleep in case it was woken up before
+ * and set the default prescale value
*/
pca9685_set_sleep_mode(pca, true);
+ regmap_write(pca->regmap, PCA9685_PRESCALE, PCA9685_PRESCALE_DEF);
pm_runtime_set_suspended(&client->dev);
pm_runtime_enable(&client->dev);

--
2.29.2
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